Welte



May 18, 1943 B. WELTE HYDRAULIC BROACHING MACHINE s Sheets-Sheet 1' Original Filed April 22, 1938 INVENTOR fiezrezz cz fl elie.

May 18, 1943 B. WELTE HYDRAULIC BROACHING MACHINE Original Filed April 22, 1938 5 Sheets-Sheet 2 h. RNEYS May 18, 1943 B, WELTE Re. 22,318

HYDRAULIC BROACHING MACHINE Original Filed April 22, 19158 5 Sheets-Sheet 25 INVENTOR ,BzJcaiZ'Z Well e.

A ORNEY5- May 18, 1943 B. WELTE HYDRAULIC BROACHING MACHINE Original Filed April 22, 1938 5 Sheets-Sheet 4 INVENTOR B 71:47; cz #42126.

BY M we,

TORNEY May 18, 1943 wELTE Re. 22,318

HYDRAULIC BROACHING MACHINE Original Filed April 22, 1938 5 Sheets-Sheet 5 NVENTOR ,Bezrzaiz'l 14 Z M BY fizz :44 ATToRNEY Reissued May 18, 1943 maavuc aaosonnm moms Benedict Wcltc we on Township. om County, and, llllmr to' Colonial Brooch Company, Detroit, Mich a corporation of Delaware Original No.

2,255,332, dated September 15,

1941, Serial No. 203,854, April 22, 1938. Application for reissue June 2, 1942, Serial No. 445,499

27 Claims.

This invention relates to hydraulic circuits and the control valves therefor.

The main objects of this invention are to provide a hydraulic circuit control for a machine having three hydraulic cylinders which are required to move through a continuous cycle; to provide a hydraulic circuit control for three hydraulic cylinders where two of the cylinders may be for broaching rams and the third cylinder for moving the work supports toward and away from the respective breaches; to provide a positive inmain cylinders is completed before movement the third or work shitting cylinder is possible; to

provide a quick and positive stop of all moving members in case 0! emergency; to provide an arrangement in which the moving parts may be returned to starting position following an emergency stop, and to provide an arrangement in which the last moving part is the first to'retum to its starting position after an emergency stop followed by reversing.

An illustrative embodiment of this invention is shown in the accompanying drawings, in which:

Figure l is a diagrammatic view of the improved hydraulic circuit, and various control valves therefor;

Figures 2, 3 and 4 show the improved hydraulic circuit of Figure l, but with the valves in each case in the positions they assume during different portions of the cycle 01' operation of the machine;

Fig. 5 is a fragmentary section taken alon the line 5-5 of Figure l; and Fig. 6 is an enlarged, sectional, detail View, showing how the lever 59 may be released from connection with the control plungers MI and III.

In the drawings, which are somewhat diagrammatic, a main hydraulic fluid pump 5 and secondary hydraulic fluid pump 5 are driven by an electric motor I. Fluid is supplied to the pumps irc-m a reservoir 5 through an intake conduit 5 having branches l0 and ii to the pumps 5 and 5, respectively.

The main fluid pump 5 discharges through a may flow around them.

conduit l2, a pressure relief valve l8, and conduit it, into a port i5 of a primary control valve, generally designated II. The valve I! may be any desired iorm oi pressure relief valve, such as the conventional iorm illustrated and described in connection with valve 45 hereinafter. It diilers from the valve 45 only in that it omits the pilot line control of the valve 49.

The primary control valve i5 comprises a casing having a cylindrical bore l1 therethrough in which is axially slidable a valve spool IS. The spool it comprises a plurality oi bore fitting, cylindrical, axially spaced, lands l9, 2i), 2!, 22, 25 and 24 Joined by reduced neck portions which permit the passage of fluid axially within the limits of any two lands. The interior wall of the bore i1 is provided with axially spaced, encircling grooves. or ports [5, 25, 28, 21, 28, 29 and 30, which are positioned so as to be controlled by the lands of the spool l8.

' One end of the valve spool II is formed to provide a spring centering means comprising an integrally formed, axially extending rod 5|, surrounded by a helical compression spring 32, the opposite ends of which bear against washers l3 and 34 which are slidable on the rod ii. The outer end oi the rod it has a set collar 25 rigidly flxed thereon, washers II and I4 and collar III are all oi slightly smaller diameters than the bores in which they flt with the result that oil In addition, washers 33 and 34 are provided, respectively, with auxiliary holes 35A and "A adapted to permit the flow or oil through them from one side of the washers to the other. The casing of the valve I5 is provided with a shoulder 35 against which the floating washer it shuts, and an end wall plate 51 against which the floating washer I3 abuts, after the usual manner of spring centering devicesof this character. Ports 25 and 25 of the main control valve i5 are connected by lines 25A and 28A to a fluid return line 55, and port 29 is also connected to the return line 55 through a by-pass valve 25A, which operates to permit flow from port 29 to line 55 when the pressure in port 29 exceeds a predetermined value. The by-pass valve 25A may be oi any conventional form, such as that illustrated and described in connection with valve 41 hereinafter.

The ports 26 and 21 01' the valve i5 have pri mary pressure line conduits I8 and I8 communicating therewith, hereinafter referred to as the primary circuit, which conduct fluid under pressure to and from a pair of vertically disposed hydraulic broaching tool or work performing cylinders 40 and 4|, respectively, through manifolds 42 and 41, respectively. The lines II and II pass through pistons "A and "A, respectively, so as to introduce fluid into their respective cylinders below the pistons in order to force the cylinders downwardly.

Fluid discharged under pressure from the secondary pump 8 passes through a line 44 to branch fines is and u. The line It connects through a by-D Ss valve 41 and line 48 to a pressuFe relief valve 49, thence through a line I to afluid pressure operated four-way secondary control valve ii. The relief valve 49 is connected to a fluid return line 54 by a line 49A. The secondary valve II has pressure working lines I2 and II connected thereto, hereinafter referred to as the secondary circuit, and a fluid return line 64, which connects with a fluid return line 55. The line 55 leads to and discharges into the tank or reservoir 8.

The function of the by-pass valve 41 is to prevent the flow of fluid under pressure to line 40 until the pressure in lines 44 and 46 reaches a predetermined value, as pointed out hereinafter. The valve 41 is a conventional form of pressure responsive by-pass valve having a spool 41A adapted to control communication between ports connected to lines 45 and 44. The spool is normally urged toward the right, as viewed in Figure l, by an adjustable spring 413, in which position the lefthand land on the spool closes communication between lines 45 and 48. The valve body, however, contains a small passage 41C connecting the port associated with line 45 to the valve bore at the righthand end of the spool "A, with the result that the pressure in line 45 constantly acts on the righthand end of the spool, urging it to the left in opposition to the spring 413. When this pressure reaches a value sumcient to overcome the force of the spring, the valve opens and permits flow from line 45 to line 48. when the pressure drops below that value, the spring closes the valve.

The valve 49 is a conventional form of pressure relief valve which functions to connect lines 48 and 50 to the low pressure tank, or reservoir, I under certain conditions. The valve is provided with a spool 49B adapted when it shifts to the right, as viewed in Figure 1, to close the port in communication with the discharge line 49A. This spool is normally urged in a direction to close the port associated with line 49A by a spring 496'.

with the discharge line 49A. when the discharge port is closed, there is free communication between lines 48 and 50, and the pressure at the righthand side of the piston 49D is balanced by reason of the fact that the same pressure is transmitted through the bleed opening 49E to the opposite side of the piston. Under normal operating conditions, the pressure in lines 48 and 50, which pressure acts through the bleed opening ICE, is insufiicient to lift the spring-pressed ball valve 48(3- of! its seat. However, if the pressure in lines 48 and 5B exceeds a predetermined amount suilicient to raise ball valve 49G, the fluid at the lefthand side of the piston 49D flows past the valve 49G to the spring housing at thelefthand end of the body and thence through the valve spool bore 49F to the discharge line 49A. This causes a drop in pressure at the leithand side i of the piston 49D, because the flow through the The spool is provided with a piston 49!) which fits I the bore of the valve body and which is subject at one side to the pressure in the lines 48 and 50. The piston 49D, however, has a small bleed opening 49E therethrough which serves normally to balance the pressures on opposite sides of the piston. The lefthand end of the spool 49B flts in a spring bore of the housing, and the space at the lefthand side of the piston 491) is adapted to be connected to this spring bore by a passageway containing a spring-pressed ball valve 49G. The valve 49G normally closes communication through this passageway.' The spring bore in the body is also connected to the discharge line 49A through a bore 49F through the spool 493. The space within the valve body at the lefthand side of the piston 49D is also connected to a pilot line 200. The operation of the valve is as follows:

Spring 49C normally shifts the spool 4913 into a position in which it closes the port connected bleed opening 49E is restricted. As a result, the pressure acting on the righthand side of piston 49D opens the valve and vents the lines 49 and 50 to the reservoir 8. The same result may be effected at any time by connecting the pilot line 200 to the reservoir, since this likewise lowers the pressure at the lefthand side of piston 49D causing the valve to open the port connected with the discharge line 49A.

The valve 5| is a conventional pilot operated four-way valve having a valve spool provided with three lands adapted to control the ports in communication with the lines ill, 52, 53 and 54. When the spool is in the position shown in Figure 1 of the drawings, free flow is permitted from the pressure line 50 to the line 52 through the space between the lefthand and central lands on the spool. At the same time, return flow is permitted from line 53 to line 54 through the space between the central and righthand lands on the valve spool. when the spool is in its lefthand position, free flow of pressure is permitted from line 50 to line 53 through the space between the central and righthand lands on the spool, and at the same time return flow is permitted from line 52 to line 54 through the space between the central and lefthand lands on the spool. The position of the valve spool is controlled at all times by pilot pressure admitted through lines 262 and 203 to the ends of the spool bore. In the position shown in Figure 1, pressure is applied through line Iii! to shift and hold the spool to the right, and line 203 is connected to the reservoir.

The secondary circuit lines 52 and it are connected to axially aligned, integrally formed, hollow piston rods 56 and 51 of a work moving hydraulic cylinder 58 which is disposed transversely with respect to the work performing cylinders 40 and 4|. The cylinder 58 is adapted to be connected to a pair of work supporting fixtures, or the like, for alternately moving work toward and away from the broaching or work performing cylinders 40 and 4|. Fluid from the lines 52 and BI passes out through apertures 59 and SI formed in the hollow piston rods 56 and 51, respectively, closely adjacent to a stationary piston 8| upon which is slidable the cylinder 58, it being understood that the piston rods 56 and 5'! are plugged between the apertures 59 and lill so as to prevent fluid from passing from one line to the other.

The details of construction of the work moving cylinder 58 and the work performing cylinders 40 and 4|, with the machine in which they are mounted, are shown in the joint application of applicant and Albert H. Worden, Serial No.

199,756, filed April 4, 1938, issued December 17,

1940, as Patent No. 2,229,191, and assigned to the assignee of this invention.

The line 49 carries fluid through a branch line 92 to a control valve, generally designated 99, and through a branch line 94 to a control valve generally designated 99. The control valve 99 is provided with a cylindrical bore 99 in which is axially slidable a valve spool 91. The spool 91 is provided with bore fitting, cylindrical, axially spaced, lands 99, 99, 19 and 1|, connected by reduced neck portions which permit thetlow oi fluid axially between the lands in the usual manner.

The cylindrical bore 99 has its interior wall provided with axially spaced, encircling ports 12, 19, 14, 19 and 19, which are positioned so as to be controlled by the lands of the spool 91. The spool 91 is provided at one end with anintegrally formed, axially extending rod 11 which, through a lever 19, is connected to a spring centering device 19.

The spring centering device 19 comprises a collar 99, helical compression springs 9| and 92 which bear against opposite sides or the collar 99 and the respective ends of a stationary housing. The collar 99 is secured to a rod 99 which passes axially through the housing and which is connected to one end of a lever 94, the other end of which is in position to be engaged by depending lugs 99 and 99 carried by the hydraulic cylinder 99.

Ports 12 and 19 of the control valve 99 are connected by branch lines 91 and 99, respectively, to a fluid return line 99 which empties into the return line 99, and thence into the reservoir 9.

The control valve 99 is provided with a cylindrical bore 99 in which is axially slidable a valve spool 9|. The spool 9| comprises bore fitting, axially spaced, cylindrical lands 92, 99, 94 and 99, which are connected by reduced neck portions in the usual manner. One end of the valve spool is provided with an integrally formed, axially extending rod 99, the outer end of which is pivotally connected to one end of a lever 91, the other end oi which is connected to one end 01' a control rod 99. The other end of the rod 99 is connected to one end a lever 99 which is rockable on an axially slidable pivot I99. 'As best shown in Figs. 5 and 6, the lever 99, at points equidistantly spaced at opposite points oi the pivot I99, is detachably connected to plungers IM and I92, which are positioned to contact lugs I99 and I99A, carried by the main broaching cylinders 49 and 4|, respectively, for shifting the plungers to rock the lever 99, and thereby through the links, move the spool 9| axially in its bore. The lever 99 is normally held in engagement with the plungers I9I and I92 by a compression spring 99A.

It is to be understood that the drawings are diagrammatic to a great extent inasmuch as the elements involved are well known to those skilled in the art. The plunger I92 is shorter than the plunger I9I, and when the plunger I92 is contacted and moved by the lug I99, the linkage moves to a central position, at which time both ends of the plunger IllI protrude slightly beyond the ends of the plunger I02 so that the cam lug I95A may pass by the ends of the plunger I92 but will contact and move the plunger IM to the opposite position.

The lugs I99 and I94 and the plunger I94 are all in the same vertical plane, which is ofiset from a common vertical plane which contains lug I99A, lug I99, plungers I9I and I92. The width of lug I94 and also the length oi plunger I94 must be such that when lug I94 comes opposite to plunger I94, it wlllbeshiitediothe right an equal amount as It is shown to the left now.

The interior wall of the cylindrical bore 99 of valve 99 is provided with axially spaced, encircling port grooves I99, I99, I91. I99 and III, which are positioned so as to be controlled by the lands of the spool 9|. The ports I99 and I99 communicate with the fluid return line 99 through lines "9 and III, respectively.

The ports 19 and I9 01 valve 99 are connected to lines H2 and H9, respectively, which conduct fluid to and from a control valve, generally designated II4. Control valve III is provided with a cylindrical bore I I9 in which is axially slidable a valve spool III, which has bore fitting. cylindrical, axially spaced lands H1, H9, H9 and I29 connected by reduced neck portions in the usual manner. One end of the spool H9 is provided with an integrally formed, axially extending rod I2 I the outer end of which is pivoted to the'outcr end of an arm I22 of a bell crank lever rockable on fixed pivot I29. The other arm I24 0! the bell crank lever is connected to one end 01 a link I29 by a slot and pin connection I29. The other end of the link I29 is pivoted to the outer end oi an arm I21 which is integrally formed on the lever 91.

The interior wall of the bore N9 of valve H4 is provided with axially spaced, circling port grooves I29, I29, I99, III and I92, which are positioned so as to be controlled by the lands of the spool H9. The ports I29 and I9I are connected to lines I99 and I94, respectively, which lead to a manually operable control valve generally designated I99.

The valve I99 is provided with a cylindrical bore I99 in which is axially slidable a valve spool I91. The spool I91 comprises bore fitting, axially spaced, cylindrical lands I99, I99 and I49, which are connected by reduced neck portions in the usual manner. One end oi. the spool I91 is provided with an integrally formed axially extending rod I, the outer end of which is rigidly connected to a cross head I42.

.The interior wall of the bore I99 of valve I99 is provided with axially spaced, encircling port grooves I49, I44, I49, I49 and I41, which are positioned so as to be controlled by the lands of the spool I91. The ports I49 and I41 are connected to lines I49 and I49 respectively, which join in line I99. The line I99 leads to and conducts fluid to the control valve I9 at the righthand end thereof, the communication being to that part of the valve casing which houses the valve centering means.

The port I49 of valve I99 is connected to a line I9I which leads to the opposite end of the control valve I9 for carrying fluid into the casing to shift the valve spool II to the right therein. as shown in the position illustrated in Fig. l of the drawings. The lines I99 andI9I; lines I99 and I94; and lines II! and H9 are hereinafter icierred to collectively as the primary pilot circuit.

The ports I99 and I99 of control valve 99 are connected to lines I92 and I99, respectively, which lead to a control valve generally designated I94 in which is axially slidable a valve spool I99. The spool I99 comprises bore iitting, axially spaced, cylindrical lands I99, I91 and I99 Joined by reduced neck portions in the usual manner. .O'nc md oi the spool is provided with an integrally formed, axially extending, rod I99. to the outer end. of which is pivoted one end of a link I99 which passes through a spring centering device |8| of the same general construction as the centering device 18. The other end of the link I50 is pivoted to one end of a lever I82 fulcrumed at I88. The lever I82 carries a plunger I84, one end of which is adapted to be engaged and actuated by a lug I85 carried by the broaching cylinder 4i, and the other end of which is adapted to be engaged by a lug I04 of the cylinder 40, for rocking the lever I82 and thereby shifting the spool I55 axially in its bore.

The cylindrical bore I88 of the valve I54 is provided with axially spaced, encircling port grooves I81, I88, I88, I10, and "I, which are positioned so as to be controlled by the lands of the spool I55.

The port I88 of control valve I54 is connected to the port I80 of control valve 4 by a line I12, and the port I88 is also connected to the return fluid line 88 by a line I13.

The line I52 has a branch pre-flll line I14, which passes through a check valve I15, and thence to a line I18, one end of which communiztes with the port 80 of valve I8, and the other end of which passes through'manifoid 43, and thence to the interior of broaching cylinder 4| above the piston 88A for moving the cylinder upwardly.

The line I53 has a branch pre-flll line I11 connected thereto which passes through a check valve I18, and thence to a line I18, one end of which communicates with the port 28 oi valve I8, and the other end of which passes through the manifold 42 and into the broaching cylinder 40 above the piston 88A, for moving the cylinder upwardly. The lines I14 and I11 are hereinafter referred to as the pre-fill circuit and the lines I18 and I18 are hereinafter referred to as the closed circuit.

Ports I88 and I of control valves I54 are provided with lines I80 and I8I, respectively, which communicate with a manually operable control valve, generally designated I82. The valve I82 is provided with a cylindrical bore I83 in which a valve spool I84 is axially slidable. The spool I84 comprises bore fitting, cylindrical, axially spaced lands I85, I08, I81, and I88, connected by reduced neck portions which permit flow of fluid axially within the limits of any two of the lands. One end of the spool I84 is provided with an axially extending rod I88 which is rigidly connected to the cross head I42 so that the spools I84 and I81 may be moved in unison manually by a link I80 which is connected to a hand lever I8I.

The interior wall of the bore I88 is provided with axially spaced, encircling, port grooves I82, I88, I84, I85, I88, I81, and I88 which are positioned so as to be controlled by the lands of the spool I84. Port I88 has a line I88 connected thereto which communicates with the fluid return line 88. Port I81 has a line 200 connected there to which conducts fluid from the relief valve 48. Ports I88 and I82 are connected by lines 20I and 202 to one of the valve operating ports of the four way valve iii. The port I84 is connected by a line 208 to the other valve operating port of the four way valve 5|. The lines 20I, 202, 288, I80, I8I, I52 and|58 are hereinafter referred to as the secondary pilot circuit for operating tlze secondary control valve of the secondary circuit.

In operation, this hydraulic circuit, as heretofore stated, provides control for a machine havin: three hydraulic cylinders which are required to move through a continuous cycle. The cylmechanism for moving work into position to be operated on by tools which are actuated by the cylinders 40 and 4|.

After the movement of the cylinder 58 is compieied, the cylinders 40 and 4| again begin to move in opposite directions as before, and upon reaching their new end position, the cylinder 58 moves in the opposite direction, thus bringing the diflerent moving members back into their original position. From this point on, the movements repeat themselves, as described above, thereby forming a continuous cycle.

This cycle of movements can be used to operate vertical double ram broaching machines where the cylinders 40 and 4| operate slides which in turn carry broaching tools, and the cylinder 58 operates a work table with two workholding flxtures in such a way as to put one fixture in cutting position and retracting the other fixtures away from the upgoing broach slide, allowing it ix; be unloaded and reloaded with a new work p ece.

In Figure 1 is illustrated the position of the parts at the instant of the starting of the machine. The directlon of flow through the lines and valves of the circuit is indicated by the solid line arrows, while dotted line arrows are used to indicate the direction in which pressure is exerted in the absence of flow. In this position of the parts, the hydraulic pump 8 is supplied with fluid from the reservoir 8 through the intake lines 8 and II, and delivers fluid under pressure through the lines 44, 48, and 82 to the port 14 of the valve 88, and through the line 84 to port I01 of the control valve 85. From port I01 the fluid passes axially along the spool 8| into port I08, and thence into lines I52 and into port I81 of valve I54. From port I81 the fluid passes axially along the spool I55 to port I 88, thence into line I toport I83 of valve I82. From port I83 the fluid passes axially along spool I84 to port I82, and thence into line 202 which leads to one of the operating ports of the four way valve 5|. Pressure in the line 202 holds the spool of the valve 5| to the right, as viewed in Figure 1 in such a way as to connect the intake line 50 of the valve with pressure line 52, and at the same time connect line 58 with fluid return line 54 which empties through the return line 55 into the reservoir 8. Fluid is supplied to the four way valve 5| through the pressure line 44, branch 45, by-pass valve 41, line 48, relief valve 48, and thence to the line 50 which communicates with the four-way valve 5|.

With the spool of the four way valve 5| thus positioned, fluid under pressure from the pump 8 has just been delivered through line 52 to the hollow piston rod 58, out through the aperture 58 therein, thereby moving the cylinder 58 to the position shown in Fig. 1 of the drawings. This causes the work holding fixture, which is connected to the cylinder, to be held in proper position in relationship to the broaching ram cylinder 4|.

At the same time, fluid from the line I52 passes mm the branch pre-flll line m, through check valve I18, and thence to the line I18, one end of which communicates with the interior of the cylinder 4| above the piston 88A therein, thus insuring the nlling of the line with fluid and raising oi the cylinder II to its topmost beginning position. The purpose of this arrangement lies malnly in the period preceding the one shown in Figure l of the drawings, and also preceding the movement of valve 8I and cylinder 88 to-the positions oi Fla. 1. At that time, the spool I8 of valve I8 is held in its mid-position by the spring 82, and when in that position the land 28 of spool I8 will be positioned between the ports 28, and 80, which blocks the port 88 from any other communicatlon. Thus, fluid entering the line I18 under pressure, moves the cylinder ll in its top position if not already in that position and supplies any loss of oil past the rings oi piston 88A, and the packing glands in the top end of the cylinder during its movement.

As soon as cylinder 88 reaches the position of Fig. 1, fluid from the port- 14 of valve 88 was conducted axially of the spool 81 to the port 18, and thence through line III to port I82 oi. valve I I4. From port I82 the fluid passed axially along the spool II8 to port I8I and thence through line I34 to port I48 of valve I88. From port I48 the fluid was .conducted axially along the spool I81 to port I48, and thence through line I8I to the left end of the valve I8, thereby moving the spool I8 to the right, as illustrated in the position shown in the drawings.

It will be noted that after the shift of valve I8 and the other parts to the position shown in Fig. 1, no further flow of fluid can occur in lines 48 and 82. This causes pressure to build up in these lines and consequently in lines 44, 48 and 48 to such an extent that the pressure relief valve 49 opens to the position shown in Fig. 1, thus venting the pump 8 and pressure line 44 to the tank 8 through lines 48A, 84 and 88. This opening movement of pressure relief valve 48 was the last movement of the parts prior to their condition illustrated in Fig. 1. Valve 48 serves to limit the pressure which is built up in the lines in communication with the valve, but when open the pressure is sufllcient to hold valve II in the position of Fig. 1 against the force of spring 82 so longas line 200 is closed by the spool of valve I82.

When the spool I8 is moved to the position shown in Figure 1 of the drawings, fluid under pressure from the main hydraulic pump 8 passes through line I2, pressure relief valve I8, line I4, port I8, axially into port 21, and thence into line 38, which leads to the cylinder 4I.

Fluid under pressure from the line 39 will pass through the stationary piston 39A and into the cylinder 4I at the lower side of the piston, thus moving the cylinder 4| downwardly on its broaching or work performing stroke. As soon as the cylinder 4| moves downwardly, the lug I88 thereon clears the plunger I84, thus permitting the spring centering device I8l, through the rod I89, to move the spool I85 to its mid-position, at which time the land I88 will cover the port HI and the land I81 will be centered over port I89 but permit passage of fluid. thereby due to the notches I88A formed therein, and the land I58 to cover the port I61 and shut off communication therethrough.

Cylinder ll, in moving downwardly, will force fluid contained above the piston 89A out through the cylinder 88 moves upwardly, the lug I88 will disengage from plunger III and contact plunger I82, moving it to the right from the position shown in the drawings, and thereby through'link 88, lever 81, and rod 88, move the spool II to its mid-position. When spool 8i is moved to mid-position, communication between ports I01 and Ill is interrupted, which thereby shuts oi! further preflll action through the check valve I18 to the line I18. Spool II8 of valve H4 is not affected by movement of the link 98, lever 81, arm I21, and link I28, dueto the slot and pin connection I28, thus leaving the valve in the position shown in the drawings.

Downward movement or the cylinder 4| continues until the lug INA engages the plunger III, at which time the lever 88, and link 88, is moved to the left as shown in Figure 2 or the drawings. When moved to this position, -the lever 81, through rod 88, moves the spool 8| to its extreme right hand position, and through arm I21 and link I28, bell crank I22, I24, and rod I2I, the valve H8 is moved to its extreme right hand position.

Movement of the spool ill to its extreme right hand position causes the port I82, which is connected to pressure, to be cut oil? from port III by the land II8 of spool H8, and at the same time connects the port III with the port I88, which, through line I12, communicates with port I88 01 valve I84. From port I88 the fluid is vented through line I18 to the fluid return line 89, thence to the reservoir 8. This ventingot the fluid enables the spring 82 of the spring center means of valve I8 to move the spool I8 to its mid-position shown in Fig. 2, the fluid from the left end of the cylinder being vented through line I8I, port 8, port I48, line I84, port I8l, port I88, line I12, and thence through lines I18 and 88 to the reservoir 8.

In order to let the spool I 8 move freely, it is also necessary to connect line I88 through branch I48, port I", part I48, line I88, port I28, port I28, line 2, port 18, port 12, line 81 to line 88, and thence to the reservoir 8.

the line I18 into port 88, thence to port 28, and

The movement of the spool I8 to its mid-position serves a two-fold purpose. First, the land 28 is moved in between the ports 28 and 88, thereby shutting ofl communication between the two ports, which arrests, through hydraulic lock the movement of the cylinder 4|. Second, the lands 28 and 2| are moved over ports 28 and 21, respectively. Fluid delivered now by the pump 8 is lay-passed through the slots 28A and 2IA, remectively, to tit ports 28 and 28, thence through the return lines 28A, 28A, and 88 to the reservoir 8.

The work performing hydraulic cylinder 48 should theoretically reach its extreme top position when the lug I88A contacts plunger ill, but in practice two conditions have to be consldered. The first is when the cylinder 48 reaches its top position ahead of time. In this case the cylinder 4I continues to move downwardly. and the oil displaced from the cylinder above the piston 88A is forced out through the line I18 into the port 80, but can no longer pass from the port 28 into the line I18 due to the fact that the cylinder 48 has reached its top limit or movement. In such a case the fluid is forced out through pressure relief valve 29A into the return flow line 55, and thence returned to the reservoir 5. The second case is where the cylinder 40 lags behind in its movement and does not reach the upper limit of its stroke by the time the cylinder 4I is forced down to the lower set limit of its stroke. As has been explained before, when cylinder 4I reaches the bottom of its stroke, the spool M has been moved into the position shown in Figure 2 of the drawings. Pressure fluid from the port I01 now enters the port I08, and thence into line I58. Port III is blocked by land I58 of spool I 55, by reason of the spring centering device II which holds the spool I55 in mid-position, the land I55 covering the port I'll for the reason that the plunger I54 has not as yet been contacted by the lug I04 of the cylinder 40. Therefore, the only way for this fluid to go is through the line I", check valve I I5, and thence to the line I15, thereby forcing the cylinder 40 on upwardly to its topmost position, at which time the lug I04 will cam the plunger I54 to the right, thereby forcing the spool I55 to its right hand position, shown in Figure 2.

when the spool I55 is moved to its right hand position, the fluid under pressure in the port III will now flow axially of the spool to port I10, and thence into line I5I which communicates with the port I55 of valve I82. From port I95 the fluid flows axially of the spool to port I54, and thence into line 203 which leads to one of the valve spool operating ports of the four-way valve 5|. The fluid under pressure coming in from the line 203 will now shift the spool in the four-way valve 5| so that fluid entering through the line 50 into the valve will pass out through the line 53 of the secondary circuit, thence to the hollow piston rod 51 and out through the aperture 50 therein into the left hand end of the work moving hydraulic cylinder 58, thereby moving the cylinder 55 to the position opposite to that shown in Fig. l with respect to its stationary piston 5|. Figure 2 of the drawings illustrates the position of the valves and parts during movement of the cylinder 58 from its right hand to its left hand position. The cylinder 58 may be connected to work holding fixtures in such a manner as to move one fixture away from the hydraulic cylinder 4| which has just completed its down stroke and move another work holding fixture into position to be operated on by the hydraulic cylinder 40 when it is next moved downwardly.

It is to be noted that movement of the work shifting cylinder can take place only after both of the work performing cylinders 45 and 4I have reached their proper positions by reason of the shifting of the spools ill and I55, which shifting is done only when the cylinders 40 and 4| have reached their limit positions, at which times the lug I04 or the lug I55 shifts the plunger I54, and either the lug I03 or lug I55A shifts the plimger IOI. It will thus be seen that it requires the shifting of both of the spools 5| and I55 before reversal of pressure takes place in the pilot lines 202, 203, which control the four way valve 5I, which in turn controls the secondary pressure circuit comprising the lines 52 and 53. Such an arrangement is very important to the satisfactory operation of a dual ram broaching machine.

As the work moving cylinder 58 moves to the left, as just described, the lug 85 disengages from the upper end of the lever 84 and permits the spring centering device 15 to shift the sp l 31 in a left hand direction to its mid-position. The

completion of the movement of the cylinder 55.

the lug 85 will contact the upper end of lever 54 and move it to the position shown in Figure 3 of the drawings, thereby shifting the spool 51 to its extreme left hand position. When in that position, fluid under pressure from the line 52' and port 14 will enter the port 13, line I I2, port I25, and, due to the fact that the spool III has been shifted to the right, fluid will flow from port I25 into port I25, thence into line I33 to port I44 of valve I35. From port I44 the fluid will pass axially along the spool I31 to port I43 into line I45, thence into line I50 and into the right hand end of the main control valve I5, thereby shifting the' spool I5 to the left, i. e., to the position shown in Figure 3 of the drawings.

When the spool I8 is shifted to the left, fluid from the left end of the valve is vented through line I5I, ports I45 and I45, line I34, to port I3I. The spool II5 having been shifted to the right so that the land II! is to the right of port I3I, the fluid will flow into port I30, thence to line I12, to port I58 of valve I54. From port I55 it will flow into line I13 to the fluid return line 88, thence through line 55 into the reservoir 5. After spool l5 has been shifted to the left as shown in Fig. 3 valve 45 will open as previously explained to bypass pump 5 as clearly shown in Fig. 3.

The spool I5 having moved to its new position of Figure 3 of the drawings, fluid under pressure is delivered by the pump 5, through line I2, pressure relief valve I3, and line I4 into port I5. From port I5 fluid will flow axially along the spool I5 into port 25, thence into line 35 of the primary circuit which includes the lines 38 and 35. The line 38 leads to the work performing cylinder 40 which is in its upper position and passes into said cylinder below the piston 38A therein, thereby forcing the cylinder downwardly on its work performing stroke. From here on, the operation of the parts is the same as that heretofore described, with the exception that the cylinders and linkage controls are just the opposite to that hereinabove described. It will thus be seen that there is a positive interlock between the movements of the three hydraulic cylinders 40, H, and 55. If either of the cylinders 40 and H are not in their extreme position, then the spools 9| and I55 of the valves 55 and I54 will be in their mid-position, whereby the flow of fluid under pressure to the pilot circuit 202, 203, of the four way valve II is blocked and no movement of its spool takes place; therefore, no change in the 5 position of work moving cylinder 58 is possible.

Furthermore, when the cylinder 55 is away from either .one of its and positions, the spring centering device 18 will hold the spool 51 in its mid-position, thereby blocking fluid under pressure in the port I4 from reaching either the port 78 or port I5, which two ports finally lead to the lines I55 and I5I, which communicate with opposite ends of the main control valve I5 for shifting the spool therein. The lands 55 and I0, however, have notches 55A and 10A, respectively, which connect the ports I3 and I5 withthe lines 81 and 58 through the respectively adjacent ports I2 and .15. This will equalize any difference of pressure which might exist in the lines I50 and lil and thereby enable the spring centering device of the valve I5 to centralize the spool I5, which thereupon blocks movement of the cylinders 40 and H by reason of the land 23 of spool I5 moving in between the ports 25 and 30, while at the same time permitting fluid from the pump 5, lines I2 and I4,.to be vented by by-passing through the notches 25A and 2IA, and thence to the return lines 25A and 28A to the return line 55.

During long periods of idleness, it may be that the closed circuit comprising the lines I18 and I18 have lost large amounts of fluid. For instance, consider the situation when the machine is set at full stroke. The various parts have just reached the position shown in Figure l of the drawings and the motor is shut off so that the pump comes to rest before anymovement of the spool in the four way valve 5| has taken place. It is further assumed that the machine is now allowed to rest for a length of time during which the cylinder 4| sinks down a considerable distance from its top position, but not so far as to make the lug 5A contact the plunger Il.

Now it is assumed that the motor is turned on again and fluid from the pump flows under pressure through the lines 44, 46, and 84 to the port I01, thence to port I08, line I52, line I14, 1

check valve I15, to line I18. From line I16 the fluid will flow into the cylinder 4| above the piston 58A, thereby raising the cylinder upwardly to its top position. This is made possible by reason of the spool I8 being held in its midposition by the spring 82 of the spring centering device, and the land 23 shutting off communication between the ports 28 and 50. As the cylinder 4| is thus raised to its top position, fluid is.

return fluid line 55 which leads to the reservoir 8.

. During all this time no fluid is admitted to four way valve 5| until the prefill action brings the cylinder 4| to its top position where the lug I85 cams the plunger I84 to the left against the spring centering device I5I, and thereby shifts the spool I55 to the position shown in Figure 1 of the drawings. When shifted to this position, fluid from port I51 will pass axially to port I58, and thence to line I80 which leads to port I83. From I83 the fluid will flow axially of the spool I84 to port I82, and thence to line 202 of the pilot circuit which operates the spool of the four-way valve 5|.

Shifting of the spool in valve 5| permits fluid under pressure from the pump 5 through lines 44, 45, by-pass valve 41, line 48, pressure relief valve 48 and line 50 to enter the line 52 of the secondary circuit, and thence into the right hand end of the cylinder 58 which moves the cylinder to the right, as shown in the drawings.

Consider the machine when the cylinders 40 and 4| are in the position shown in Figure l of the drawings, and the work moving cylinder 58 is in its extreme left hand position, and the spool in the valve 5| has been shifted preparatory to the cylinder 58 moving to the right. is assumed now that the motor I is shut oil and the machine not used for a considerable length of time. The cylinder 4| under the influence of gravity may sink down from its top position. This creates a hazard, as tools mounted on the slide driven by the cylinder 4| might interfere with any flxtures which would be carried into position in relation to the cylinder 4|, if it would move as the cycle demanded. Now, upon restarting the motor 1, fluid delivered by the pump 8 will flow first through the lines 44, 46,

and 54, ports I01 and I05, line I52, line I14, check valve I15 to line I15, and thereby replenish the fluid on top of piston 88A 0! cylinder 4|, and thereby lifting the cylinder 4| back to its top 5- position. I

The cylinder 58 will not move during this, preflll action because the by-pass valve 41 is set at a sufllciently high pressure so as to not allow any fluid to flow through it until after the cylinder 4| has reached its top position, at which time further flow through the line 45 is resisted, and the valve 41 is forced open, thereby permitting fluid to flow through the lines and thus resume the normal cycle of operation.

It is to be further noted that fluid under pressure in the line 48 passes through line 82 into port 14, port 18, line II2, to port I28 of control valve H4, at which point it is blocked due to the land III being in position between the ports I28 and I28. Also, the fluid passing through the line 54 to port I01, port I08, line I52, to port I81, is also blocked by reason of the fact thatthe spring centering device I5I has moved the spool I55 to the right to its mid-position immediately upon the lug I55 disengaging from contact with the plunger I54.

Considering the machine in a position where the cylinders 48 and 4| are in the position as shown in Figure l of the drawings; the cylinder 58 has started out on its trip to the right and the motor 1 has been shut off. It is assumed that after the cylinder 4| has left its top position, the motor 1 is turned on again. As heretofore explained, the by-pass valve 41 will prevent any flow of fluid to the four-way valve 5|, and cylinder 58 until the preflll action is complete. The cylinder 58 being away from its end position, the spool 81 will be in mid-position, thereby preventing any flow of fluid from the port 14 to either of the ports 13 or 15. Fluid is thus blocked from the line 82 and forced to the line 54 and thence to the preflll circuit.

Consider now the same case of the top cylinder 4| dropping during idleness, but with the machine set at less than full stroke. The difference in this case is that the cylinder 40 is also affected by gravity, and will lose position. In such an instance, no interference between tools and fixtures and work pieces will take place because gravity will carry the cylinder 40 down away from the tools. Therefore, it is not necessary to make provision to correct position of cylinder 40 before resuming the normal cycle of operation. Advantage has been taken of this fact. The preflll action through check valves I15 and I18 is controlled through the valve 55. Preflll is started ateither extreme position of the spool 8| and shut off in its center position. Nowthe ascending cylinder 40 will shut ofi this preflll by centering the spool 8| through the plunger I02, link 88, lever 81, and rod 88. The dropping of cylinder 40, however, will not aflect the position of the spool 8| because the centering action is caused in this case not by an automatic centering device, but by mechanical linkage which is only effective in one direction.

Considering now the case where the machine being set on part stroke of cylinders 40 and 4| is allowed to stand idle, that cylinder 4| sinks to a position where the lug |A is below the plunger IOI. In this case the circuit will not automatically correct the position of the cylinders, and a manual prefill has to be used. As shown most clearly in Fig. 6 of the drawings, the lever 88 is pivoted on an axially slidable shaft I00, and this shaft can be moved axially to the right, as viewed in Fig. 6, against the action of spring 99A whereby it is disengaged from the plungers MI and I02, but maintains connection with the link 99. Now, by turning this shaft I manually, the spool 9| may be shifted to either extreme position, thereby admitting fluid under pressure from port I01 to either port I09 or I09, and thereby raising either the cylinder 40 or 4I upwardly at the will of the operator until one of the lugs I03 or I55A gets above the plunger IOI, from which point on, the circuit takes care of any further movement.

The above described disengagement of the lever 99 from the piungers IOI and I02 is provided to make the manual prefill independent of the position of the plungers III and I02, inasmuch as they may become locked by being contacted simultaneously by the lugs I03 and I95A. No interference can be created by this manual preflll action. The work moving cylinder 59 cannot move due to the spring centering device IN and by-pass valve 41. Furthermore, the cylinder which was originally in the top position will always be able to return to its top position without interference because the position of cylinder 59 must havebeen such that the cylinder 4I could sink down without interfering with fixture controlled by the cylinder 59.

With respect to the stopping of all moving members in case of emergency, or the like, such functioning is controlled by the manually operable valves I25 and I92, the spools I31 and I94, respectively, of which are rigidly connected to a cross head I42 which in turn is connected through the link I90 to a manual control handle I9I.

In order to stop the operation of all parts of the machine, the lever I9l is moved to the center position, shown in dotted outline. This causes the spools I31 and I94 to move to their center position. The land I39 of spool I31 will now stand midway over the port I45, and the land I40 will be midway over the port I41. Now the pilot line II of the main control valve I9, will communicate through port I45, slots I39A, slots I40A, port I41 and line I49 with pilot line I50 at the other side of the spool I9, thereby balancing hydraulically regardless of pressure conditions in the ports I44 and I45, and allowing the spring 32 to move spool I 9 to its mid-position, which, as heretofore pointed out, hydraulically locks cylinders 40 and 4| by blocking communication between the ports 29 and 30, with the land 23, while at the same time allowing fluid delivered by the main pump 5 to be by-passed through the slots A and 2IA. This stops the movements of the cylinders and H under any conditions, and vents the pump 5.

The mid-position of the spool I94 provides communication between ports I91 and I99, and allows fluid to flow from pressure relief valve 49 through the line 200 to port I91 axially along the spool to the port I99, and thence through line I99 to the fluid return line 99, line 55 to reservoir 9. Due to the particular construction of the valve 49, which construction constitutes no part of the present invention, unrestricted flow through the line 200 will cause the relief valve 49 to allow fluid to be by-passed through the line 49A to line 54, thence to line 55 and to the reservoir 9 at a pressure much lower than necessary to move the cylinder 59 and thereby stop its motion immediately.

After the machine has been stopped by moving the manual control handle III to its center position, either by reason of emergency, or otherwise,

it may then be necessary to reverse the movements of all of the parts and return them to the positions from which they started, and from there again start out in the normal cycle of operation.

Assume that the machine is in the position shown on the drawings and that the cylinder H has started down on its work performing or cutting stroke, it being assumed that this cylinder is carrying a breaching tool and on its down stroke will pirform a broaching operation on a work piece clamped on a fixture which is held in position in certain relationship to the broaches or other tools carried by the cylinders 40 and M. It is further assumed that for some unforeseen reason the resistance offered to the breaching tools by the work piece is greater than the power developed in the cylinder M. This causes the machine to "stall."

In order to correct this condition with a minimum amount of damage to the broaching tools and the other component parts, it is best to pull the broaches up out of the work piece without releasing the work piece from its clamped position and then move the work holding fixture out of the cutting position into loading position in order to enable the operator to correct the faulty condition. This is accomplished automatically by moving the hand lever I9I into the extreme right position. Figure 4 of the drawings shows the position of the parts when the lever I 9| is shifted to its reversing positionat a time when the cylinder-4| is moving down. The valves 63 and H4 have not changed from the position of Figure 1 but the spool I31 in valve I35 has been shifted to its extreme right hand position. This causes fluid under pressure to flow from lines 46 and 52 into port 14, thence to port 15, line II3 to port I32. From the port I32 the fluid will flow axially to port I3 I, thence to line I34 which leads to port I45. From port I46 to the port I41, thence through lines I49 and I50 to the right hand end of the main control valve I5, thereby shifting the spool I9 to the left, the fluid being vented from the left end of the valve I6 through line I5I to port I45, port I44, line I33, port I29, port I30, line I12, port IE9, line I13. to fluid return line 99, and thence to reservoir 9.

This positioning of the valve causes fluid from the pump 5 to pass through the main circuit line 39 to the under side of the piston 39A, thereby reversing the motion of the cylinder 40, and moving it down to the position from which it started. As heretofore described, this will cause the cylinder M to move upwardly towards its top position, from whence it started. During this motion of the cylinders 40 and 4i, the valves and I54 are in their mid-position, and fluid from the lines 45 and 94 is blocked from leaving the four way valve 95 through the ports I05 and I 09. This makes ineffective at this time any movement of the spool I94, as caused by hand lever I9I. The position of the cylinder 59 will be maintained until the cylinders 40 and 4| have returned to their starting position, as shown in Fig. 1 of the drawings, thereby shifting the spools in valves 95 and I54 out of their mid-positions into the position shown in Fig. i and allowing fluid to flow from port I01 to port I09, line I52, port I51, port I99, line I90, to port I93. Due to the reverse position of the spool I94, fluid will pass from port I99 to port I94, line 203, thence to the four. way valve 5|, thereby shifting the spool in the valve to the opposite or left position and causing fluid from the line 50 to flow through line 59,

hollow piston rod 51, to the left hand side of the piston II, thereby causing the cylinder 58 to. move to the left and thereby moving the fixture in question out of the cutting position and into the loading position.

The cylinder I, upon leaving the position shown in Fig. 4, permits the spring centering device I! to move the spool 61 in valve 83 to its midposition. Movement of the valve to mid-position causes lines I50 and iii leading to valve II to be connected to the reservoir 8 through line Ill, port I45, port. I, line I33, port I", port Illl, line I12, port-I68, line I13, line 89, and line ll. The line IIl is vented through port I41, port I46, line I34, port Iil, port I32, line Ill, port 15, slots 'IIIA, lines I, I9, and 55 to reservoir 8. The spool III will move to its mid-position, thereby locking cylinders 40 and ll and venting the pump 5 back to the reservoir. This helps to keep the hydraulic system at low temline does not pass through the valve 63. Also,

the line IIII continues to be vented'through the valve N, the land III now being moved entirely clear of the port I5. Therefore, no further movement will take place and the cylinders 40, 4| and II will come to rest and give the operator an opportunity to make correction of whatever was the cause of the stalling of the machine.

After the fault has been corrected, and in order to lead the machine back into its normal operating cycle, the hand lever Isl is moved to the left to the position shown in full lines in Fig. 1, and which position may be marked Go." As heretofore stated, both ends of the main control valve I0, through the lines I50 and III, are connected to the reservoir 8, and shifting of the spool I" does not have any immediate effect.

The four way valve II, however, is under control pressure of the line "I, and upon shifting the spool Ill withthe handle m, this control fluid is switched to the opposite line 20!, thereby shifting the spool in the valve SI and reversing the flow oi fluid from the pump I to cause the work moving cylinder 58 to move to the right. This is the position shown in Fig. 1, and the hydraulic action will take place, as described before, as the machine is new again on its regular cycle.

Another case has to be provided for, and that is where the operator loads a work piece in the wrong manner which would cause damage if the machine were allowed to proceed with its cycle. If the operator wishes to return the work moving cylinder SI to its starting position after it has left the starting position but before movement of the cylinders 40 and ll has begun, he again puts the hand lever ISI in the reverse position. The hydraulic condition thereby created is identical with the one heretofore described. The cylinder II will reverse and go back where it came from, and no further movement-will take place, the

cylinders II and ti being locked against movement during this time. Upon making correction on the loading of the work piece, the hand lever "I may be moved into the go position, and the movements take place in the same manner as heretofore described for the regular and normal cycle of operation of the machine.

The construction and arrangement herein shown and described permits an operator by manipulating the handle IQI to move any one of the three hydraulic cylinders in extremely small increments, generally referred to as an inching" process. That is to say. the moving parts can be stopped in very short distances and moved very short distances, which is of considerable advantage in setting up a machine incorporating this hydraulic circuit for locating the parts in exact position as is so often wanted.

In order to more readily comprehend the meaning of the claims, the following is a summary of the main features. The pump I is referred to as a primary pump; the primary circuit comprises the lines 38 and as; the primary valve is the pressure operated control valve generally designated I6; and the primary pilot circuit comprises the lines IIII, IBI, III, Ill, III and III. The pump 6 is referred to as the secondary pump; the secondary circuit comprises the lines I! and I53; the secondary valve is the four way fluid pressure operated valve III; and the secondary pilot circuit comprises the lines 2, 202, 20!, IBII, I8I, I52 and IE3. The preflll circuit comprises the lines I'll and I", and theclosed circuit comprises the lines I18 and I19.

Formal changes may be made in the specific embodiment of the invention disclosed without departing from the spirit and substance of the broad invention, the scope of which is commensurate with the appended claims.

What is claimed is:

1. In a hydraulic circuit, a primary circuit, a pair of work performing hydraulic cylinders having one end of each connected in said primary circuit, a valve for controlling said primary circuit so as to move said cylinders simultaneously, in opposite directions, a secondary circuit, a work moving hydraulic cylinder connected in said secondary circuit, a single closed circuit interconnecting the opposite ends of said work performing hydraulic cylinders during movement of either cylinder on its work performing stroke, means for blocking said closed circuit to prevent movement of said work performing cylinders during movement of said work moving cylinder, and means for supplying fluid under pressure to all of said circuits. 7

2. In a hydraulic circuit having a continuous cycle of operation, a primary circuit, a pair of work performing hydraulic cylinders connected in said primary circuit, a closed circuit connecting said cylinders for moving either one of said cylinders when the other is moved by fluid pressure from said primary circuit, means for prefllling said closed circuit, interlocking means for preventing operation of said cylinders on continuous cycle until said closed circuithas been prefilled, and means for supplying fluid under pressure to all of said circuits.

3. In a hydraulic circuit, a primary pressure circuit, a pair of work performing hydraulic cylinders connected in said primary circuit, a primary valve for controlling the flow of fluid to said cylinders, a primary pilot circuit connected to said primary valve for actuating the same, a secondary pressure circuit, a work moving reciprocating hydraulic cylinder connected in said secondary circuit, a secondary valve for controlling the flow of fluid to said work moving cylinder, a secondary pilot circuit connected to said secondary control valve for actuating the ame,

a-control valve actuated by saidwork moving cylinder for controlling the flow oi fluid to said 4. In a hydraulic circuit, a primarycircuit, a

pair of work performing hydraulic cylinders in' said primary circuit, a primary valve for said primary circuit, a primary pilot circuit for. moving said primary valve, a circuit, a work moving hydraulic cylinder in said secondary circuit, a secondary valve for controlling said secondary circuit, a secondary pilot circuit for operating said secondary circuit valve, a valve actuated by said work moving cylinder for controlling said primary pilot circuit, a valve actuated by said work performing cylinders for. controlling said secondary pilot circuit, and means for supplying fluid under pressure to said circuits.

5. In a hydraulic circuit, a primary circuit, a pair of work performing hydraulic cylinders in said primary circuit, a primary valve for said primary circuit, a primary pilot circuit for moving said primary control valve. a secondary circuit, a work moving hydraulic cylinder in said secondary circuit, a secondary valve for controlling said secondary circuit, a secondary pilot circuit for operating said secondary circuit valve, a valve actuated by said work performing cylinders for controlling said secondary pilot circuit, a valve actuated by said work moving cylinder for controlling said primary pilot circuit, means for supplying fluid under pressure tojsaid circuits. and manually operable valves for controlling both of said pilot circuits.

6. In a hydraulic circuit, a primary circuit, a pair of work performing hydraulic cylinders in said primary circuit, a primary valve for said primary circuit, a primary pilot circuit for moving said primary control valve, a secondary circuit, a work moving hydraulic cylinder in said secondary circuit, a secondary valve for controlling said secondary circuit, a secondary pilot circuit for operating said secondary circuit valve, a valve actuated by said work performing cylinders for controlling said secondary pilot circuit. a valve actuated by said work moving cylinder for controlling said primary pilot circuit, a closed circuit connected ,to s'aidwork performing cylinders for" moving either one of said work perfumingcylinders when the other'is moved by said primary circuit, and means for supplying fluid under pressure tosaid circuits.

7. In a hydraulic circuit, a primary circuit, a pair of work performing hydraulic cylinders in said primary circuit. a primary valve for said primary circuit, a primary pilot circuit for moving said primary control valve, a secondary circuit, a work moving hydraulic cylinder in said secondary circuit, a secondary valve for controlling said secondary circuit, a secondary pilot circuit for operating said secondary circuit valve, a valve actuated by said work performing cylinders for controlling said secondary pilot circuit, a valve actuated by said work moving cylinder for controlling said primary pilot circuit. a closed circuit connected to said work performing cylinders for moving either one of said work performing cylinders when the other is moved by said primary circuit, means for supplying fluid under pr'essureto said circuits, and manually operable valves for controlling both of said pilot circuits.

8. In a hydraulic circuit, a primary circuit, a pair of work performing hydraulic cylinders in said primary circuit, a primary valve for said primary circuit, a primary pilot circuit for moving said primary control. valve, a secondary circuit, a work moving hydraulic cylinder in said secondary circuit, a secondary valve for control- 11m; said secondary circuit, a secondary pilot circuit for operating said secondary circuit valve, a valve actuated by said work performing cylinder for controlling said secondary pilot circuit, a valve actuated by said work moving cylinder for controlling said primary pilot circuit, a closed circuit connected to said work performing cylinders for moving either one of said work performing cylinders when the other is moved by said primary circuit, means for prefllling said closed circuit, a

valve actuated by said work performing cylinders for controlling such preflll, and means for supplying fluid under pressure to said circuits.

- 9. In a hydraulic circuit, a primary circuit, a pair of work performing hydraulic cylinders in said primary circuit, a primary valve for said primary circuit, a primary pilot circuit for moving said primary control valve, a secondary circuit, a work moving hydraulic cylinder in said secondary circuit. a secondary valve for controlling said secondary circuit, a secondary pilot circuit for operating said secondary circuit valve, a valve actuated by said work performing cylinders for controlling said secondary pilot circuit, a valve actuated by said work moving cylinder for controlling said primary pilot circuit, a. closed circuit connected to said work performing cylinders for moving either one of said work performing cylinders when the other is moved by said primary circuit, means for prefliling said closed circuit, a valve actuated by said work performing cylinders for controlling such preflll, means for supplying fluid under pressure to said circuits, and manually operable valves for controlling both of said pilot circuits.

10. In a hydraulic broaching machine, a pair of broaching cylinders, a normally closed circuit connecting one end of each of said broaching cylinders, means for supplying iluidunder pressure alternatively to the opposite ends of said broaching cylinders to elect asimultaneousbroaching stroke of one cylinder and a return stroke of the other cylinder followed bya simultaneous return stroke of said one cylinder and a broaching stroke of said other cylinder, means acting automatically between the completion or a broaching stroke of one of the cylinders and the institution of the broaching stroke of the other cylinder to feed a workpiece into position to be broached by said last mentioned cylinder, and means acting throughout the period between the completion of the broaching stroke of one of the cylinders and the institution of the broaching stroke of the other cylinder to apply fluid under pressure to the closed circuit end of the last mentioned cylinder.

11.Inahydraulicbroachingmachine,apair I of broaching cylinders. a normally closed circuit connecting one end of each of said broaching cylinders, means'for supplying fluid under pressure alternatively to the opposite ends of said broaching cylinders to effect a simultaneous broaching stroke of one cylinder and a reiairn stroke of the other cylinder followed by a simultaneous return stroke of said one cylinder and a broaching stroke of said other cylinder, means throughout said period to effect a preflll of said normally closed circuit.

12. In a hydraulic broaching machine, a pair of broaching cylinders, means for alternatively supplying pressure fluid to said broachlng cylinders at one end of each for moving the cylinders through their broaching strokes, a closed circuit normally connecting the opposite ends of said broaching cylinders to effect return of one cylinder during the broaching stroke of the other, a work movingcylinder adapted at each extremity of its stroke to present work in position to be broached by one of said broaching cylinders, means operable when said broaching cylinders have completed a stroke for reversing the position of said work moving cylinder, means acting on completion of one stroke of said broaching cylinders to prevent a reverse stroke of the broaching cylinders untilthe work cylinder has completed its movement, means for blocking said normally closed circuit at a point between said cylinders throughout the period between the completion of the broaching stroke of one cylinder and the institution of the succeeding broaching stroke of the other cylinder, and means for connecting said last mentioned cylinder, to a source of pressure throughout said period to effect a preflll of said closed circuit.

13. In a hydraulic broaching machine, a broaching cylinder adapted to reciprocate through a broaching stroke and a return stroke, a work moving cylinder adapted to shift a workpiece into and out of broaching position, means for supplying fluid under pressure to said work moving cylinder to shift the same from a starting position in which the workpiece is retracted from said broaching position into a position in which the workpiece is in broaching position, means operable automatically upon completion of the movement of the workpiece into broaching position for suppplying fluid under pressure to said broaching cylinder to shift the same from a starting position through the broaching stroke, and manually con-trolled means operable at any time during the aforesaid movements of said cylinders for automatically returning both of said cylinders to their starting positions in reverse order and direction to the order and direction in which they left said starting positions.

14. In a hydraulic broaching machine, a broaching cylinder adapted to reciprocate through a broaching stroke and a return stroke; a work moving cylinder adapted to move a workpiece into and out of position to be broached; a hydraulic circuit for said cylinders; circuit control means for continuously operating said cylinders through a cycle from a starting position in which the work moving cylinder has shifted the work out of broaching position and the broaching cylinder is in position to begin the broachlng stroke to eflect the successive steps of advancing the work to broaching position,

broaching the work, and returning the work and the breach to starting position, and manually controlled means operable at any time during the work advancing movement and the broaching stroke to cause the cylinders to be returned from the position they then occupy to the starting position in reverse order and direction to the order and direction in which they last leit said starting position.

15. In a hydraulic broaching machine, a broaching cylinder adapted to reciprocate through a broaching stroke and a return stroke; a work moving cylinder adapted to move a workpiece into and out of position to be broached; a'hydraulic circuit for said cylinders; circuit-con trol means for continuously operating said cylinders through a cycle from a starting position in which the work moving cylinder has shifted the work out of broaching position and the broaching cylinder is in position to begin the broaching stroke to eflect the successive steps of advancing the work to broaching position, broaching the work, and returning the work and the broach to starting position, and manually controlled means operable when actuated during the broaching stroke to flrst reverse the broaching cylinder and return it to starting position and then return the work moving cylinder to starting position.

16. In a hydraulic broaching machine; a broachlng cylinder adapted to reciprocate through a broaching stroke and a return stroke; a work moving cylinder adapted to move a workpiece into and out of position to be broached: a hydraulic circuit for said cylinders; circuit control means for continuously operating said cylinders through a cycle from a starting position in which the work moving cylinder has shifted the work out oi broaching position and the broaching cylinder is in position to begin the broaching stroke to eflect the successive steps oi advancing the work to broaching position, broaching the work, and returning the work and the broach to starting position, and manually controlled means operable when actuated during movement of the work moving cylinder in a direction to place the workpiece in broaching position to reverse the direction of motion of the work moving cylinder-and return it to starting position.

17. In a hydraulic broaching machine, a pair of broaching cylinders, means for reciprocating said broaching cylinders simultaneously in opposite directions, a work moving cylinder adapted on reciprocation to moving work alternatively into working position with respect to said broach operating cylinders, fluid pressure means for automatically shifting said work moving cylinder to one end of its stroke between successive broaching strokes of the broaching cylinders to shiit a workpiece into position to be broached by the cylinder next makingits broaching stroke, and manually controlled means operable at any time to cause reverse and return the broaching cylinders to the ends of their strokes if they are intermediate the ends of their strokes and thereafter reverse the position of the work moving cylinder.

18. In a hydraulic broaching machine, a pair of broaching cylinders, means including a primeans including a secondary valve for reciproeating said work moving cylinder, a primary pilot circuit for actuating said primary valve. 21 secondary pilot circuit for actuating said secendary valve, a valve in said primary pilot circuit operable by and upon completion of a stroke of the work moving cylinder to shift the primary valve and eiiect a breaching stroke of the breaching cylinder into relation with which the workpiece was moved-and a return stroke of the other breaching cylinder, a valve in said secondary pilot circuit operable by and upon completion of a stroke of one of said breaching cylinders to eilect a shift oi the secondary valve and a reversal oi the position of the work moving cylinder.

19. In a hydraulic breaching machine, a pair of breaching cylinders, means including a primary valve for eflecting simultaneous reciprocation of said breaching cylinders in opposite directions, a work moving cylinder adapted on reciprocation to move workpieces alternatively into breaching position with respect to said cylinders,

means including a secondary valve for reciprocating said work moving cylinder, a primary pilot circuit for actuating said primary valv'e, a secondary pilot circuit for actuating said secondary valve, a valve in said primary pilot circuit operable by and upon completion of a stroke oi the work moving cylinder to shift the primary valve and eil'ect a breaching stroke of the breaching cylinder into relation with which the workpiece was moved and a return stroke of the other breaching cylinder, a valve in said secondary pilot circuit operable by and upon completion of the breaching stroke oi one of said breaching cylinders and a return stroke of the other'to eflect a shift of the secondary valve and a movement oi a workpiece into breaching position with respect to the other breaching cylinder.

20. In a hydraulic breaching machine, a pair of breaching cylinders, means including a primary valve for eiIecting simultaneous reciprocation of said breaching cylinders in opposite directions, a work moving cylinder adapted on reciprocation to move workpieces alternatively into breaching position with respect to said cylinders, means including a secondary valve ior reciprocating said work moving cylinder, a primary pilot circuit for actuating said primary valve, a secondary pilot circuit for actuating said secondary valve, a valve in said primary pilot circuit operable by and upon completion of a stroke of the work moving cylinder to shiit the primary valve and eil'ect a breaching stroke of the breaching cylinder into relation with which the workpiece was moved and a return stroke of the other breaching cylinder, a valve in said secondary pilot circuit operable by and upon completion oi a breaching stroke of one of said breaching cylinders to eiifect a shift of the secondary valve and a movement oi a workpiece into breaching position with respect to the other breaching cylinder, and.manually controlled means for reversing both pilot circuits to shift both the primary and secondary valve and eflect automatic sequential reversal oi said cylinders in reverse order to their previous order oi movement.

21. In a hydraulic breaching machine, a source oi fluid under pressure, a vertically movable breaching slide, a hydraulic piston and cylinder for operating said slide, a hydraulic motor for moving a workpiece into and out oi breaching position, automatic control devices for controlling the flow oi. fluid to and from said cylinder and meter to move the breach and work successively through a cycle in which the motor advances the work to breaching position, the breaching slide moves downwardly. on its breaching stroke, the motor retracts the work and the breaching slide is returned to its upper position. means to prevent advance or the work by said control means when the breaching slide is not in its fully returned upper position, and means operable automatically to fully return the breach to its upper position when said last mentioned means is acting to prevent advance of the work.

22. In a hydraulic breaching machine, a source of fluid under pressure, a vertically movable breaching slide, a hydraulic piston and cylinder for operating said slide. a hydraulic motor for moving a workpiece into and out oi breaching position, and automatic control devices for controlling the flow oi fluid to and i'rom said cylinder and motor to move the breach and work successively through a cycle in which the motor advances the work to breaching position, the breaching slide moves downwardly on its broaching stroke, the motor retracts the work and the breaching slide is returned to its upper position, said automatic control devices including a conduit from said pressure source having connections to said cylinder and motor, and a valve in the fluid connection to said motor for blocking flow through said connection to the motor until the pressure in said conduit exceeds that required to return the breach to its fully returned upper position.

23. In a hydraulic breaching machine, a source of fluid under pressure, a vertically movable breaching slide, a hydraulic piston and cylinder i'or operating said slide, a hydraulic motor for moving a workpiece into and out of breaching position, and automatic control devices for controlling the flow of fluid to and from said cylinder and motor to move the breach and work successively through a cycle in which the motor advances the work to breaching position, the breaching slide moves downwardly on its broaching stroke, the motor retracts the work and the breaching slide is returned to its upper position, said automatic control devices including a device for controlling actuation of the motor, and'means operable automatically upon actuation of said device in a direction to cause advance of the work into breaching position to render said device ineffective to cause advance of the work so long as the breaching slide is not in its fully returned position, said last named means being automatically eiiective to return said piston and cylinder and the breaching slide to their fully returned position.

24. In a hydraulic broachini machine, a source of fluid under pressure, a vertically movable breaching slide, a hydraulic piston and cylinder for operating said slide, a hydraulic motor for moving a workpiece into and opt oi breaching position, a hydraulic operating circuit connecting said source with said cylinder and motor and adapted to eiIect a cycle of successive movements of said breaching slide and workpiece in which the workpiece is advanced by the motor, the breaching slide is moved downward on its breaching stroke by the piston and cylinder, the workpiece is retracted by the motor and the breaching slide is returned to its upper position, said circuit including a valve means for controlling the direction of movement of said hydraulic motor, control means for shifting said valve means to a position in which it causes said motor to advance the work to breaching position, means rendering said control means ineflective to nun said valve to said position when the broaching slide is not in its uppermost position, and means automatically eifective to return said broaching slide to its uppermost position when said last named means is rendering said control means ineifective to shift said valve.

25. In a hydraulic breaching machine, a source of fluid under pressure, a vertically movable broaching slide, a hydraulic piston and cylinder for operating said slide, a hydraulic motor for moving a workpiece into and out of broaching position, a hydraulic operating circuit connecting said source with said cylinder and motor and adapted to eifect a cycle of successive movements of said broaching slide and workpiece in which the workpiece is advanced by the motor, the breaching slide is moved downward on its broaching stroke by the piston and cylinder, the workpiece is retracted by the motor and the broaching slide is returned to its upper position, said circuit including a valve means for controlling the direction of movement of said hydraulic motor, control means for shifting said valve means to a position in which it causes said motor to advance the work to broaching position, means rendering said control means ineffective to shift said valve to said position when the broaching slide 151101; in its uppermost position, means automatically eifective to return said broaching slide to its uppermost position when said last named means is 'Irendering said control means ineffective to shift said valve, and means operable after said valve has shifted and before the motor has completely advanced the work to broaching position to return thebroaching slide to its uppermost position if it has left said position and to prevent further advance of said work during such return.

26. In a hydraulic broaching machine, a source of fluid under pressure, a pair of vertically movable broaching slides, a pair of piston and cylinder units for operating said slides respectively, a primary control valve for controlling the flow of fluid to said units to effect a simultaneous downward broaching stroke of one slide and an upward return stroke of the other slide, a work support movable between a position in which it presents a workpiece in position to be breached byone of said slides to a position in which it presents a workpiece in position to be breached by the other slide, means operable when either oi said slides completes its broaching stroke to shift said work support to the position in which the work will be in broaching position with respect to the other slide, means automatically operable to delay shift of said work support to said last named position in the event that the other slide is not in its fully returned position until said other slide is in its fully returned position, and means automatically eflective to cause full return of said broaching slide when said last named means is delaying shift of said work support.

2'7. In a hydraulic broaching machine, a pair of breaching cylinders, a normally closed circuit connecting one end of each of said broaching cylinders, means for supplying fluid under pressure alternatively to the opposite ends of said broaching cylinders to eflect a simultaneous broaching stroke of one cylinder and a return stroke of the other cylinder followed by a simultaneous return stroke of said one cylinder and a broaching stroke of said other cylinder, means acting automatically between the completion of a broaching stroke of one of the cylinders and the institution of the broaching stroke of the other cylinder to feed a workpiece into position to be breached by said last mentioned cylinder, means for blocking said normally closed circuit at a point between said cylinders throughout the period between the completion of a broaching stroke of one of the cylinders and the institution of a broaching stroke of the other cylinder, means for applying fluid under pressure to the closed circuit end of the last mentioned cylinder throughout said period to eflect a preflll of said normally closed circuit, and means to prevent operation of said automatic workpiece feeding means until said closed circuit end of said last mentioned cylinder is completely filled.

BENEDICT WELTE. 

